Sexton joined the U.S. Army as a paratrooper in the 82nd Airborne Division in 1970. The division, however, had just returned from Vietnam, so he never saw any action. While he was in the army, he taught ballroom dancing and one of his clients convinced him to try being a salesman, which he continued to do after his two-year enlistment was up. After a while, he realized that he could make more money playing poker than being a salesman, so he took up poker in 1977.

Although Sexton frequented tournaments, he was never able to make it to the World Series of Poker because he coached Little League baseball teams and the schedules overlapped. In 1985 he moved to Nevada to pursue poker full-time. Sexton was a well known cohort of poker player Stu Ungar. Upon Ungar's death, Sexton was a pallbearer and speaker at his funeral.

As of 2010, Sexton has won several tournaments, including one World Series of Pokerbracelet, and over $5,400,000 in total tournament winnings.[2] He won his bracelet in the $1,500 Seven card stud split event at the 1989 World Series of Poker. His 46 cashes at the WSOP account for $910,792 of his total winnings.

However, Sexton is better known for his promotion of various poker events and services. He is the commentator of the World Poker Tour, alongside Vince Van Patten, and spokesman for PartyPoker.com, an online poker room. He has written for Card Player Magazine and the Gambling Times. He also founded the now defunct Tournament of Champions of Poker, which only let tournament winners from the previous year compete.

For all of his work promoting poker, Sexton is often known as the "ambassador of poker". Because of his affiliations, however, Sexton is unable to play in some poker events. Although the number of games he plays currently is less than before, he states that he doesn't mind so much, having played for so many years. Sexton did finish 10th in a preliminary event at the 2005 World Series of Poker and also in the final 16 of Poker Superstars II.

On February 15, 2006, Sexton was recognized as the top poker ambassador at the Card Player Magazine Player of the Year Awards Gala.

On June 27, 2006, Sexton won the third annual World Series of Poker Tournament of Champions event, and along with it the $1,000,000 first prize. In the final hand, his A♥A♣ defeated Daniel Negreanu's Q♥J♥ on a board of 10♦8♦4♠A♦8♣. Sexton later donated half of his post-tax winnings to five charities, and has pledged to do the same with all future winnings.[3]

Sexton was selected for the Poker Hall of Fame in 2009.

In early 2009, Sexton along with Linda Johnson, Jan Fisher and Lisa Tenner, created PokerGives.org, a nonprofit organization that offers poker players an easier way to give to charity.[4]

In July 2012, Sexton finished in 9th place in the "Big One For One Drop" WSOP event, earning him $1,109,333 dollars, the biggest cash of his career.